/*
 * Copyright (C) 2012 STMicroelectronics
 * Matteo Dameno, Denis Ciocca - Motion MEMS Product Div.
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdint.h>
#include <errno.h>
#include <unistd.h>
#include <poll.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/types.h>

#include <linux/input.h>

#if defined(PLTF_LINUX_ENABLED)
#else /* PLTF_LINUX_ENABLED */
#if (ANDROID_VERSION >= ANDROID_P)
#include <log/log.h>
#else
#include <cutils/log.h>
#endif
#endif /* PLTF_LINUX_ENABLED */

#include "InputEventReader.h"

/*****************************************************************************/

struct input_event;

InputEventCircularReader::InputEventCircularReader(size_t numEvents)
	: mBuffer(new input_event[numEvents * 2]),
	mBufferEnd(mBuffer + numEvents),
	mHead(mBuffer),
	mCurr(mBuffer),
	mFreeSpace(numEvents)
{
}

InputEventCircularReader::~InputEventCircularReader()
{
	delete [] mBuffer;
}

ssize_t InputEventCircularReader::fill(int fd)
{
	size_t numEventsRead = 0;
	if (mFreeSpace) {
		const ssize_t nread = read(fd, mHead, mFreeSpace * sizeof(input_event));
		if (nread<0 || nread % sizeof(input_event)) {
			return nread < 0 ? -errno : -EINVAL;
		}

		numEventsRead = nread / sizeof(input_event);
		if (numEventsRead) {
			mHead += numEventsRead;
			mFreeSpace -= numEventsRead;
			if (mHead > mBufferEnd) {
				size_t s = mHead - mBufferEnd;
				memcpy(mBuffer, mBufferEnd, s * sizeof(input_event));
				mHead = mBuffer + s;
			}
		}
	}
	return numEventsRead;
}

ssize_t InputEventCircularReader::readEvent(input_event const** events)
{
	*events = mCurr;
	ssize_t available = (mBufferEnd - mBuffer) - mFreeSpace;
	return available ? 1 : 0;
}

void InputEventCircularReader::next()
{
	mCurr++;
	mFreeSpace++;
	if(mCurr >= mBufferEnd) {
		mCurr = mBuffer;
	}
}
